Children who were separated from their parents last week and are being detained at the border can be heard sobbing as a U.S. Customs and Border Protection agent jokes, “We have an orchestra here,” in an audio recording obtained by ProPublica. The agent continues, “What’s missing is a conductor.” In the recording, the children repeatedly cry “Mami” and “Papá,” and one girl begs someone to call her aunt. In April, the Trump administration announced a “zero-tolerance” policy for illegal immigration and has since separated 2,300 children from their parents at the border. The policy has received condemnation from moderate Republicans including House Speaker Paul Ryan and Democrats like Trump’s former opponent Hillary Clinton.